1.4.1 Red Snapper

The red snapper fishery has separate management for the recreational and commercial sectors.

The regulations for the recreational fishery are set each year. If NOAA Fisheries determines that a season is allowed, the recreational season for the Red Snapper fishery opens the second Friday in July. The recreational sector will be open for harvest for 2 days, before being closed to retention again. The recreational fishery is managed with a bag limit of one fish per trip per angler.

The commercial fishery has a 75 lb gutted weight trip limit, and a commercial annual catch limit (ACL; 124,815 lbs whole weight in 2023). The commercial fishery is closed to retention from August 31 to July 10 the following year. The fishery is then open until the ACL is caught, and is then again closed to retention to the end of August the following year.

The red snapper fishery currently does not have a size limit for the recreational or commercial sectors.

The annual catch limit for the entire stock is split between the recreational (71.93%) and the commercial (28.07%) fleets.

More information on the current management regulations for the red snapper fishery is available here.

1.4.2 Gag Grouper

The gag grouper fishery has separate management for the recreational and commercial sectors.

The recreational fishery is closed to retention from the beginning of January to the end of April each year. Recreational fishers have a bag limit of 1 fish per day.

The recreational fishery is closed to retention from the beginning of January to the May 1 each year. Commercial fishers have a trip limit of 1000 lbs (gutted weight).

A minimum legal length of 24 inch (total length) in in place for both commercial and recreational fishers.

The annual catch limit for the entire stock is split between the recreational (49%) and the commercial (51%) fleets.

More information on the current management regulations for the gag grouper fishery is available here.

2.1.1 Calculating Seasonal Fleet Structure

The red snapper OM was based on the most recent stock assessment (SEDAR 73). This assessment included six fleets:

1. Commercial Handline (cHL)
2. Commercial Handline - Discards (cHL.D)
3. Recreational Headboat (rHB)
4. Recreational Headboat - Discards (rHB.D)
5. General Recreational (rGN).
6. General Recreational - Discards (rGN.D).

The Discard fleets include both discarded catch from the closed seasons and discards that occur during the fishing season. To be able to evaluate management actions such as different season lengths, or minimum size limits, the operating model requires a different fleet structure to that used in the assessment.

The fleet structure for the operating model requires the removals to be split into On-Season (landings and discards that occur during the mini-seasons when the fishery is open) and Off-Season (discards of all catch when the fishery is closed). This results in an OM with 6 fleets:

1. Commercial Handline - On-Season
2. Commercial Handline - Off-Season
3. Recreational Headboat - On-Season
4. Recreational Headboat - Off-Season
5. General Recreational - On-Season
6. General Recreational - Off-Season

The SEDAR 73 model was converted to the OM with the On- and Off-Season structure with the following steps:

1. Combine Landings and Discards from each fleet into Total Removals
2. Calculate proportion of Total Removals taken during On- and Off-Season for each fleet and year
3. Allocate proportion of total fishing mortality for each fleet into On- and Off-Seasons based on the proportion of removals in each season.

This process requires information on the proportion of total removals that occur during the On- and Off-Seasons, as well as information on the selectivity and retention patterns of the fleets during these seasons.

The steps are described in more detail below.

2.1.1.2 Calculate proportion of Total Removals taken during On- and Off-Season

The On- and Off-Season fleet structure was generated by calculating the proportion of total removals for each fleet that were taken during the open and closed seasons.

2.1.1.2.1 Commercial Handline

The proportion of total removals taken during the open and closed seasons for the Commercial Handline fleet was calculated from the Commercial logbook data, filtered to only include records from the SAMFC region.

Information on the dates when the fishery was open and closed for the Commercial Handline fleet was obtained from Table 2.2.1 in the SEDAR 73 report. The first seasonal closure occurred in 2010, so the Off-Season Commercial Handline fleet had zero catches until 2010.

The values for discard mortality for the Commercial Handline fleet were taken from Table 6 in the SEDAR 73 report. The discard mortality was used to calculate the number of dead discards from the reported number of fish that were discarded alive in the logbooks.

The relative fishing mortality for the On- and Off-Seasons was calculated as the proportion of total removals that occurred during the open and closed seasons (Figure 2.1).

2.1.1.2.2 Recreational Headboat

The proportion of total removals taken during the open and closed seasons for the Recreational Headboat fleet was calculated from the Headboat logbook data, filtered to only include records from the SAMFC region.

Information on the dates when the fishery was open and closed for the Recreational Headboat fleet was obtained from Table 2.2.2 in the SEDAR 73 report. The first seasonal closure occurred in 2010, so the Off-Season Headboat fleet had zero catches until 2010.

Note: assumes Recreational Headboat fleet follows recreational fishing season

The values for discard mortality for the Recreational Headboat fleet were taken from Table 6 in SEDAR 73 report. The discard mortality was used to calculate the number of dead discards from the reported number of fish that were discarded alive in the logbooks.

The relative fishing mortality for the On- and Off-Seasons was calculated as the proportion of total removals that occurred during the open and closed seasons (Figure 2.1).

2.1.1.2.3 General Recreational

The relative pattern in fishing mortality for the On- and Off-Season components of the General Recreational fleet was assumed to be the same as the Recreational Headboat fleet (Figure 2.1).

Further analyses of data from the Marine Recreational Information Program (MRIP) could be used to improve the estimates of total removals that occur during the open and closed seasons for the General Recreational fleet.

Note: currently assumes General Recreational Fleet behavior is the same as Recreational Headboat. Need further analysis of recreational catch data (MRIP) to determine fraction of total removals taken during On- and Off-Seasons

Figure 2.1: The proportion of overall fishing mortality for the On-Season and Off-Season fleets for the Red Snapper fishery.

2.1.2 Allocate proportion of total fishing mortality into On- and Off-Seasons

The operating model was constructed by allocating, for each fleet, the total fishing mortality (removals) in each year between On- and Off-Season components of the fleet according to the pattern in relative F described above.

This results in an operating model with 6 fleets, with estimated landings and discards that occur during both the open and closed seasons for each fleet (Figure 2.2). The selectivity pattern of the On-Season and Off-Season fleets was assumed to be the same.

Figure 2.2: The landings and discards for the On-Season and Off-Season fleets for the Red Snapper fishery.

2.2.1 OM Seasonal Fleet Structure

The gag OM was based on the most recent stock assessment (SEDAR 71). This assessment included seven fleets:

1. Commercial Handline (cHL)
2. Commercial Handline - Discards (cHL.D)
3. Recreational Headboat (rHB)
4. Recreational Headboat - Discards (rHB.D)
5. General Recreational (rGN).
6. General Recreational - Discards (rGN.D).
7. Commercial Dive (cDV)

Similar to the Red Snapper model described above, the Discard fleets include both discarded catch from the closed seasons, and discards that occur during the fishing season. To be able to evaluate management actions such as different season lengths, or minimum size limits, the operating model requires a different fleet structure to that used in the assessment.

The fleet structure for the operating model requires the removals to be split into On-Season (landings and discards that occur during the mini-seasons when the fishery is open) and Off-Season (discards of all catch when the fishery is closed). This results in an OM with 7 fleets:

1. Commercial Handline - On-Season
2. Commercial Handline - Off-Season
3. Recreational Headboat - On-Season
4. Recreational Headboat - Off-Season
5. General Recreational - On-Season
6. General Recreational - Off-Season
7. Commercial Dive - On-Season

The Commercial Dive fleet does not have discards. As it is a targeted fishery, it does not operate during the closed seasons and therefore is only modeled as an On-Season fleet

The SEDAR 71 model was converted to the OM with the On- and Off-Season structure following the same approach used for the Red Snapper described above.

The landings- and discard-at-age from the SEDAR 73 model for the three fleets (cHL, rHB, and rGN) were combined into total removals. This results in a model that describe the total removals-at-age by year for the three fleets. The On- and Off-Season fleet structure was then generated by calculating the proportion of total removals that were taken during the open and closed seasons.

2.2.1.3 General Recreational

Following the approach used for Red Snapper, the relative pattern in fishing mortality for the On- and Off-Season components of the General Recreational fleet was assumed to be the same as the Recreational Headboat fleet (Figure 2.3).

Figure 2.3: The proportion of overall fishing mortality for the On-Season and Off-Season fleets for the Gag Grouper fishery.

Note: currently assumes General Recreational Fleet behavior is the same as Recreational Headboat. Need further analysis of recreational catch data (MRIP) to determine fraction of total removals taken during On- and Off-Seasons

2.2.2 Allocate proportion of total fishing mortality into On- and Off-Seasons

The operating model was constructed by allocating, for each fleet, the total fishing mortality (removals) in each year between On- and Off-Season components of the fleet according to the pattern in relative F described above.

As it is a targeted fishery, the Commercial Dive fleet only operates in the On-Season. This results in an operating model with 7 fleets, with estimated landings and discards that occur during both the open and closed seasons for each fleet (Figure 2.4).

Figure 2.4: The landings and discards for the On-Season and Off-Season fleets for the Gag Grouper fishery.

2.4.1 Red Snapper

The maximum fishing mortality threshold (MFMT) for Red Snapper is defined by the SAMFC as \(F_{30\%}\), and the minimum stock size threshold (MSST) as \(75\%\text{SSB}_{F30\%}\). Overfishing is defined as F > MFMT and overfished as SSB < MSST, with \(\text{SSB}_{F30\%}\) defined as the rebuilding target.

The relationship between fishing mortality and the spawning potential ratio (SPR) was calculated using the selectivity curve representing total removals in the terminal historical year (2019; Figure 2.5). This resulted in a \(F_{30\%}\) = 0.21, and MSST of 510417 (eggs 1E8; Figure 2.5).

It should be noted that the calculation of \(F_{30\%}\) and associated metrics is a function of the overall selectivity curve for the fishery, and the values will be different if the overall selectivity pattern in the future (for example, introduction of size limits, or changes in relative exploitation levels of the different fleets).

Figure 2.5: The relationship between a) fishing mortality (F) and equilibrium spawning biomass (SB) and b) spawning potential ratio (SPR) for Red Snapper. The maximum fishing mortality threshold (MFMT) is indicated with the vertical dashed line. The equilbrium SB and SPR corresponding with MFMT are indicated with horizontal dashed lines. The horizontal dotted line indicates the minimum stock size threshold (MSST), defined as 75% of SB_MFMT.

2.4.2 Gag Grouper

The maximum fishing mortality threshold (MFMT) for Gag Grouper is defined by the SAMFC as \(F_{\text{MSY}}\), and the minimum stock size threshold (MSST) as \(75\%\text{SSB}_{\text{MSY}}\). Overfishing is defined as F > MFMT and overfished as SSB < MSST.

\(F_{\text{MSY}}\) was calculated using the selectivity curve representing total removals in the terminal historical year (2019; Figure 2.6). This resulted in a \(F_{\text{MSY}}\) = 0.42, and MSST of 1330 (Figure 2.5).

It should be noted that the calculation of \(F_{\text{MSY}}\) and associated metrics is a function of the overall selectivity curve for the fishery, and the values will be different if the overall selectivity pattern in the future (for example, introduction of size limits, or changes in relative exploitation levels of the different fleets).

Figure 2.6: The relationship between a) fishing mortality (F) and equilibrium removals (metric tons) and b) spawning stock biomass (mt) for Gag Grouper. The maximum fishing mortality threshold (MFMT) is indicated with the vertical dashed line. The equilbrium spawning biomass corresponding with MFMT is indicated with the horizontal dashed line. The horizontal dotted line indicates the minimum stock size threshold (MSST), defined as 75% of SB_MFMT.

2.6.1 Selectivity and Retention Schedules

Figures 2.8 and 2.9 show the selectivity- and retention-at-age curves in the last historical year (2019) for the On- and Off-Season fleets for the Red Snapper and Gag Grouper respectively. The selectivity pattern of the On-Season and Off-Season fleets is assumed to be the same.

The selectivity and retention curves remain the same in the projection period unless changed by a management procedure. Retention curves with a maximum value less than one indicate a general level of discarding.

Figure 2.8: The selectivity- (solid line) and retention-at-age (dashed line) curves for the Red Snapper in the multi-species operating model. The plot shows the curves from the last historical year (2019).

Figure 2.9: The selectivity- (solid line) and retention-at-age (dashed line) curves for the Gag Grouper in the multi-species operating model. The plot shows the curves from the last historical year (2019).

2.6.2 Removals, Landings, and Discards

Figures 2.10, 2.11, and 2.12 show historical overall removals, and landings and discards by fleet respectively for the Red Snapper and Gag Grouper multi-species Base Case operating model.

Figure 2.10: The overall removals (1,000 t) from the historical period of the Red Snapper and Gag Grouper multi-species operating model.

Figure 2.11: The landings (1,000 t) by fleet from the historical period of the Red Snapper and Gag Grouper multi-species operating model. Note the different scale on the y-axes.

Figure 2.12: The discards (1,000 t) by fleet from the historical period of the Red Snapper and Gag Grouper multi-species operating model. Note the different scale on the y-axes.

2.6.3 Biomass and Reference Points

Figures 2.13 and 2.14 show the predicted spawning biomass and the corresponding reference points for the Red Snapper and Gag Grouper stocks in the Base Case multi-stock operating model. Both stocks are below the MSST reference point in the terminal year (2019). Red Snapper appears to be rebuilding towards MSST, while the trend for Gag Grouper is a continuing decline.

Figure 2.13: The spawning stock (eggs) for Red Snapper from the Base Case OM. The horizontal lines indicate the reference points (see Reference Point section above).

Figure 2.14: The spawning stock (1000 t) for Gag Grouper from the Base Case OM. The horizontal lines indicate the reference points (see Reference Point section above).

5.1.1 Fixed F

This management procedure sets the fishing mortality for each fleet to the mean F from the 3 last historical years (2017 – 2019):

fixedF_mean3 <- function(x, DataList, ...) {

  stocks <- unique(Fleet_Management$Stock)
  fleets <- unique(Fleet_Management$Fleet)
  nstocks <- length(stocks)
  nfleets <- length(fleets)

  # copy the internal `Fleet_Management` object
  this_Fleet_Management <- Fleet_Management 
  
  # loop over stocks and fleets
  for (s in 1:nstocks) {
    for (f in 1:nfleets) {
      # calculate mean F from 3 last historical years
      meanF <- mean(tail(DataList[[s]][[f]]@Misc$FleetPars$Find[x,],3))
      # populate the `F` value in `this_Fleet_Management` object
      this_Fleet_Management <- this_Fleet_Management %>%
        dplyr::mutate(F=replace(F, Stock==stocks[s] &Fleet==fleets[f], meanF))
    }
  }
  # call internal `Fleet_MMP` function with `this_Fleet_Management` object
  Fleet_MMP(x, DataList, this_Fleet_Management) 
}
# define as class `MMP`
class(fixedF_mean3) <- 'MMP' 

5.1.2 Fixed F with a Minimum Legal Length Limit

This management procedure sets the fishing mortality for each fleet to the mean F from the 3 last historical years (2017 – 2019) (same as above) and includes a minimum legal length for the Red Snapper and Gag Grouper:

fixedF_mean3_MLL <- function(x, DataList, ...) {

  stocks <- unique(Fleet_Management$Stock)
  fleets <- unique(Fleet_Management$Fleet)
  nstocks <- length(stocks)
  nfleets <- length(fleets)

  # copy the internal `Fleet_Management` object
  this_Fleet_Management <- Fleet_Management

  # loop over stocks and fleets
  for (s in 1:nstocks) {
    for (f in 1:nfleets) {
      # calculate mean F from 3 last historical years
      meanF <- mean(tail(DataList[[s]][[f]]@Misc$FleetPars$Find[x,],3))
      # populate the `F` value in `this_Fleet_Management` object
      this_Fleet_Management <- this_Fleet_Management %>%
        dplyr::mutate(F=replace(F, Stock==stocks[s] &Fleet==fleets[f], meanF))
    }
  }

  # Set MLL
  MLL_RS <- inch2mm(20) # 20 inch MLL
  this_Fleet_Management <- this_Fleet_Management %>%
    dplyr::mutate(MLL=replace(MLL, Stock=='Red Snapper', MLL_RS))

  MLL_GG <- inch2mm(25) # 25 inch MLL
  this_Fleet_Management <- this_Fleet_Management %>%
    dplyr::mutate(MLL=replace(MLL, Stock=='Gag Grouper', MLL_GG))

  # call internal `Fleet_MMP` function with `this_Fleet_Management` object
  Fleet_MMP(x, DataList, this_Fleet_Management)
}
# define as class `MMP`
class(fixedF_mean3_MLL) <- 'MMP'

5.1.3 Fixed Catch

This management procedure sets the removals for each fleet to the mean removals from the 3 last historical years (2017 – 2019):

fixedC_mean3 <- function(x, DataList, ...) {

  stocks <- unique(Fleet_Management$Stock)
  fleets <- unique(Fleet_Management$Fleet)
  nstocks <- length(stocks)
  nfleets <- length(fleets)

  this_Fleet_Management <- Fleet_Management
  nyears <- ncol(DataList[[1]][[1]]@Misc$FleetPars$Find)

  for (s in 1:nstocks) {
    for (f in 1:nfleets) {
      # mean last 3 years historical removals
      meanC <- mean(apply(DataList[[s]][[f]]@Misc$FleetPars$CB[x,,(nyears-2):nyears,], 2, sum))

      # populate the `Catch` value in `this_Fleet_Management` object
      this_Fleet_Management <- this_Fleet_Management %>%
        dplyr::mutate(Catch=replace(Catch, Stock==stocks[s] &Fleet==fleets[f], meanC))
    }
  }
  # call internal `Fleet_MMP` function with `this_Fleet_Management` object
  Fleet_MMP(x, DataList, this_Fleet_Management)
}
# define as class `MMP`
class(fixedC_mean3) <- 'MMP'

5.2.1 Set an Annual Catch Limit (ACL)

For a given ACL for Red Snapper, 28.07% is allocated to the Commercial fleet and 71.93% to the Recreational sector (SEDAR 73). The ACL is assumed to apply to the On-Season (directed) fleets.

For Gag Grouper, 51% of the total ACL is allocated to the commercial fishery, and the remaining 49% to the recreational sector (SEDAR 71).

For both stocks, the ACL is assumed to apply to the On-Season (directed) fleets.